Chapter 4: Chemical Properties of Soil, Soil Fertility and Nutrient Management

Chapter Summary

Living things need nutrients for growth. Where do the nutrients come from? Green plants can synthesize simple sugars (carbohydrates) from carbon dioxide (CO2), water (H2O), and energy from the sun through photosynthesis. Apart from these carbohydrates (made up of C, H, and O), all the elements necessary for life come from the soil. Soil is the storehouse of nutrients such as Ca, Mg, K, P, Zn, Cu, etc. and these nutrients move (cycle) through plants, water, and air.

Soil is made up of minerals, organic matter, and pore space which are channels for soil water and air exchange. Through weathering, minerals release the nutrient elements into soil solution and through biological activity, nutrients locked up in organic matter are likewise released into the soil solution which plants uptake as they absorb water through their roots. The soil solid particles are made up of sand, silt, and clay. Clay particles have the most reactive power and influence because of their high surface area and reactivity. As a result, they are important in ion exchange reactions that influence nutrient availability in soil solution.

When soil nutrients are depleted due to removal by plants and the soil is not able to provide an adequate supply of nutrients, it is often supplemented by fertilizer or plant residue addition. However, when fertilizer addition is not properly timed or applied, losses to erosion, surface runoff, and leaching can occur. Nutrients in soil have to be properly managed to increase crop yield, avoid excessive fertilizer use, and protect the environment. Nutrient management requires knowledge of the soil, the specific nutrient, the plant, and the environment. Soil and plant analyses are tools that are used to identify the specific nutrient that might become deficient so that it can be corrected and thereby prevent future yield losses.

Learning Objectives

Students who complete this module will know and be able to:

  • Describe how the soil cycles essential plant nutrients between plant, water and air, and also functions as the source and storehouse of nutrients for living things.
  • Explain how human activity influences nutrient balance in soil.
  • Describe ways to make the soil a sustainable natural resource and protect the environment.

Essential Questions

  • Where do the nutrients in our food come from?
  • How do nutrients cycle in soil, plant and the atmosphere?
  • How is nutrient management affected by other soil properties?
  • How can we measure and manage soil nutrient availability?
  • How does human activity influence or affect nutrient balance in soil?

Big Ideas

  • Nutrients in the soil are the nutrients for life.
  • As the demand for global food supply increases, maximizing nutrient availability in soil will become even more critical.

Additional Teaching Materials

KSKL_Chapter 4_ Chem Properties of Soils.pptx
Click to view

Supplemental Educators PPT file for Chapter 4 (PowerPoint 2007 (.pptx) 5.1MB Mar17 21)
Click the link above to download the file to your desktop or hard drive.

Educators can purchase soil samples to use in the activities from this source: AGClassroom Soil Samples

Printable Materials

Below are links to the printable PDF files used in this module. Educators may choose to print them ahead of class, or download and save them to their computer for future reference.

Soil Charge Demonstration
Nourishing the Planet High School Materials 
Nutrients needed for proper crop development 
Chemistry in plant nutrition and growth

Optional Student Worksheets for this chapter are provided below.

Student Worksheet in PDF for Chapter 4 (Acrobat (PDF) 77kB Nov7 21)
Student Worksheet in Word for Chapter 4 (Microsoft Word 2007 (.docx) 28kB Nov7 21)

Teaching Notes and Tips

Students discover the chemical properties of soil through a series of hands-on activities, video clips and reading assignments. Students examine the relationship between soil nutrients and plant health. After completing several labs and activities, they then consider the role of fertilizer in agriculture.

Time required: 750 minutes, or 15 class periods
Tools and Technology needed: 6-volt battery, copper bands, alligator clips, clay-water slurry, small glass jar or beaker, small plastic cup, foil pan to hold water, food-coloring.

Chemistry and the chemical elements found in soil are examined in this module. To complete the module, students complete a variety of activities and labs. Before beginning the module read through the lessons and acquire needed materials and technology. Download and review the extensive teaching materials, available videos, and PowerPoint presentations from Nourishing the Planet High School Materials. Print out any handouts that will be needed. In order to reduce the amount of time needed in the classroom, some activities can be assigned as homework or made optional.

The Nutrient Deficiency photos iPhone/iPad app can be downloaded ahead of class. The Investigating Calcium Deficiency lab experiment takes one class period to set up and then allowed to run for a week.

Science Standards (NGSS)

Performance Expectations

HS ESS2-6
HS ESS3-2
HS ESS3-4
HS LS2-5
HS PS1-2
HS PS1-3



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